Make sure that IdFieldType#isAggregatable is accurate. (#62903)

Before, it always returned 'true' even when the setting
"indices.id_field_data.enabled" was false.

Fixes #62897.

Author: jtibshirani

server/src/test/java/org/elasticsearch/index/mapper/IdFieldMapperTests.java

@@ -88,6 +88,7 @@ public void testEnableFieldData() throws IOException {
                 throw new UnsupportedOperationException();
             }).build(null, null));
         assertThat(exc.getMessage(), containsString(IndicesService.INDICES_ID_FIELD_DATA_ENABLED_SETTING.getKey()));
+        assertFalse(ft.isAggregatable());
 
         client().admin().cluster().prepareUpdateSettings()
             .setTransientSettings(Settings.builder().put(IndicesService.INDICES_ID_FIELD_DATA_ENABLED_SETTING.getKey(), true))
@@ -97,6 +98,7 @@ public void testEnableFieldData() throws IOException {
                 throw new UnsupportedOperationException();
             }).build(null, null);
             assertWarnings(ID_FIELD_DATA_DEPRECATION_MESSAGE);
+            assertTrue(ft.isAggregatable());
         } finally {
             // unset cluster setting
             client().admin().cluster().prepareUpdateSettings()

server/src/test/java/org/elasticsearch/index/mapper/IdFieldTypeTests.java

@@ -53,4 +53,12 @@ public void testTermsQuery() {
         Query query = ft.termQuery("id", context);
         assertEquals(new TermInSetQuery("_id", Uid.encodeId("id")), query);
     }
+
+    public void testIsAggregatable() {
+        MappedFieldType ft = new IdFieldMapper.IdFieldType(() -> false);
+        assertFalse(ft.isAggregatable());
+
+        ft = new IdFieldMapper.IdFieldType(() -> true);
+        assertTrue(ft.isAggregatable());
+    }
 }